Extension-ladder.



PATENTED JUNE 25, 1907. F. A. BOBBITT- I 2 sums- 11231 1.

EXTENSION LADDER.

APPLICATION FILED AUG- 30.1906.

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1m 2w n0 3 m w THE NORRIS PETERS CO. WASHINGTON, D. C.

P. A. BOBBITT.

. EXTENSION LADDER.

APPLICATION FILED AUG. 30, 1906.

1n: mmms PETERS co., WASHINGTON, n. c.

PATENTED JUNE 25, 1907.

ZSHEETS-SHBET 2.

FranhJLBobbiii UNITED STATES PATENT orrion.

EXTENSION-LADDER.

Specification of Letters Patent.

Patented June 25, 1907.

Application filed August 30,1906. Serial No. 332,612.

To all whom, it may concern.-

Be it known that I, FRANK A. BOBBITT, a citizen of the United States,residing at Uniontown, in the county of Bourbon and State of Kansas,have invented certain new and useful Improvements in Extension-Lad ders,of which the following is a specification.

My invention relates to improvements in extension ladders and consistsin the novel construction, combination. and arrangement of partshereinafter described, pointed out in the claims and illustrated in theaccompanying drawings, in which? Figures 1 and 2 represent front andrear elevations, respectively, of the ladder in a folded condition. Fig.3 is a transverse section taken on line III III of Fig. 2, with some ofthe parts removed. Fig. 4, is a broken side elevation of the ladder inan extended condition; Fig. 5 is an irregular section, taken on line V Vof Fig. 4. Fig. 6, is a broken section. of the outer and intermediatesections of the ladder, in a folded condition.

While the ladder may consist of any number of sections, I have in thepresent instance shown but three, comprising an outer section 1, anintermediate section 2, and an inner section 3. The lower ends 4 of theouter section are bent in opposite directions, as shown in Fig. 1, toafford a broad bearing surface for the ladder, so that there will be nodanger of the same tipping side-wise when in an' eX- tended condition.Section 1 is provided with a series of rungs 5, and a transverse brace6, which latter is located at the upper end of the section, and acts asa guide in holding section 2 in alinement with section 1.

7 designates longitudinal grooves arranged in the side pieces 8 ofsection 1 for the reception of the out turned ends of a plurality ofcrank-arms 9, carried by the intermediate section.

10 designates a pair of dogs pivotally secured to the inner portions ofsides 8 and provided with notches 11, for engaging theout turned ends 12of crank-arms 9, which latter are arranged in recesses 9 so as not tointerfere with side pieces 8.

13 designates a Windlass journaled in the lower portion of section 1.and provided at one end with a ratchet-wl'ieel let, which isnormally'engaged by a pawl 15, pivoted to the adjacent side piece 8 andadapted to be held either in or out of engagement with the ratchet-wheelby a retractile' spring 16.

One end of the Windlass shaft is provided with a crank 17 whereby it isrotated.

Intermediate section 2 consists of a pair of longitudinal side pieces18, a series of rungs 19, and two transverse braces 20 and 21, arrangedat the upper and lower portions, respectively, of the side pieces 18.Brace 20 acts as a guide for holding the inner section 3 in longitudinalalinement with section 2, and the ends of brace 21 extend into grooves 7and act as guides in holding the intermediate section in longitudinalalinement with the outer section 1.. Brace 20 also acts as a stop inlimiting the folding movement of section 2, by contacting with brace 6.

Section 2 is normally locked in a folded condition by a latch 22,pivotally secured to one side of section 1, and comprising a foot piece23, an arm, 24; and a hook 25, which latter normally engages the lowerside of an opening 26 in a face plate 27, secured to the lower adjacentside of the intermediate section 2. Hook 25 is normally held inengagement with the faceplate, as shown in Fig. 6, by means of aretractile spring 28.

The inner portions of side pieces 18 are provided with longitudinalgrooves 29 which, like grooves'7, flare at their upper ends, as clearlyshown in Fig. 6, so as to guide the out turned ends of crank arms 9, andthe similar ends of crank-arms 32, into said grooves when the ladder isbeing folded.

30 designates a pair of dogs pivotally secured to the upper portions ofside pieces 18 and intersecting grooves 29, said dogs being provided attheir upper terminals with notches 31 for engaging the out-turned endsof the crank-arms 32, which latter are arranged in recesses 33, so asnot to interfere with side pieces 18, when the ladder is folded.

34 designates by-passes extending around the front sides of the dogs andcommunicating with'the grooves 29. As the construction and arrangementof the dogs and the bypasses is identical to the similar parts ofsection 1, further illustration of the latter is considered unnecessary.

Inner section 3 consists of longitudinal side pieces 34 and rungs 35,the upper ends of the side pieces being provided with rollers 36,adapted to bear against the wall of a building while the ladder is beingextended, and thus reduce to a minimum the friction between the upperend of section 3 and said wall. Rollers 36 may also be run upon theground, when conveying the ladder from place to place, in which instanceends 4 are grasped so that the ladder may be pushed along in the mannerof a wheel-barrow. The ends of the lower-most rung 35 are slidablyarranged in grooves 29, and thus assist in holding the inner section inlongitudinal alinement with the intermediate section.

Crank-arms 9 and 32 have inturned ends 9 and 32 respectively, pivotallysecured in the longitudinal side pieces of their respective sections 2and 3.

37 designates a two-sheave block pivotally secured to a bolt 38projecting from brace 6.

39 designates a one-sheave block pivotally secured to a staple 4Oprojecting rearwardly from brace 21. 41 designates another onesheaveblock pivotally secured to a rod 42, carried by a cross-head 43, red 42being bent upwardly to prevent block 41 from interfering with block 39when the ladder is folded, (See Fig. 2).

The ladder is extended by means of windlass 13 and a cable 44, whichlatter is attached at its ends to said Windlass, and an eye 45 dependingfrom block 37. Said cable extends upwardly from the Windlass, thencethrough one side of block 37, then downwardly through block 39, upthrough the opposite side of block 37, thence downwardly through block41 and upwardly to eye 45.

Cross-head 43 consists of two transverse bars secured together, the endsof the inner one, being slidably arranged in grooves 29, while the endsof the outer one extend around the rear sides of sections 1 and 2,andterminate in forwardly extending members 46, adapted to contact withstop pins 47 projecting from the upper portions of side pieces.

The operation is substantially as follows When it is desired to extendthe inner section 3, the Windlass is turned in the direction of arrow atin order to wind the lower portion of the cable thereon. This causes thecable to draw cross-head 43 upwardly, and as the lower end of the innersection rests thereon it will be carried upwardly therewith. As

I section. 3 moves upwardly, the out-turned ends of the crank-arms 32will pass upwardly behind the dogs 30, as indicated by the arrow 1), andpush the same forward, so that they may pass out of the upper ends ofgrooves 29. Should it be desirable to stop section 3 at any point of itsupward movement, it is raised until the crank-arms nearest said pointengage notches 31, so that the weight of the section will rest upon dogs30, and the out-turned ends of the crank-arms engaging the same, thusrelieving the cable of all weight. However, should the movement ofsection 3 be checked at any point between the arms 32, pawl 15, engagingratchetwheel 14, will lock the Windlass, so that the cable cannotunwind, and allow section 3 to accidentally fall, in case crank 17 isreleased.

When it is desired to lower section 3, it is raised until the crank-armsengaging notches 31 pass above the upper ends of dogs 30, which ends areimmediately drawn into engagement with the rear sides of grooves 29 (seeFig. 6) by springs 43. Then by throwing pawl 15 out of engagement withthe ratchet-wheel and turning crank 17 backwardly, section 3 may belowered as the outturned ends of the crank-arms 32 will contact with thefront curved sides of the dogs, and be directed thereby through thebypasses 34, so that section 3 will be free to move downwardly. Whilesection 3 is being raised as above described, section 2 will beprevented from moving upwardly therewith by hook 25 engaging face-plate27. Should it be desirable to extend sections 2 and 3, section 3 isfirst raised until its lowermost crank-arms engage notches 31. Then inthis position, cross-head 43 rests a short distance below the stop-pins47, this distance being slightly greater than the distance from thelower ends of the notches 31 to the upper terminals 30 of dogs 30. Latch25 is now disengaged from the face-plate by pushing backwardly on thefoot-piece 23. This movement swings arm 24 upwardly, causing it to raisesections 2 and 3 together, so that the uppermost crankarms will remainin notches 31. As the operator continues to turn the Windlass thecross-head will be brought into contact with stop-pins 47 before it canraise section 3 high enough to disengage crank-arms 32 from the notches31. The upward movement of the cross-head being checked section 2 willnow be drawn upwardly and carry section 3 therewith. When the lower endof section 2 moves above hook 25, the latter will be drawn into contactwith a stop 50, which limits its inward movement so that when thesection is lowered it will contact with the beveled end 25 of the hookand push the latter out of its path.

What I claim as my invention, and desire to secure by Letters Patent, is

'1. In an extension ladder, a plurality of sections slidably arrangedupon each other, a Windlass mounted upon the outermost section, across-head for extending the innermost section, stops for limiting theupward movement of said cross-head, and a cable attached at its ends tothe Windlass and the outermost section, and suitably connected to theintermediate section and the crosshead.

2. In an extension ladder, a plurality of sections slidably arrangedupon each other, a Windlass mounted upon the outermost section, across-head for extending the inner most section, a latch for holding theintermediate section while the innermost section is being extended, anda cable attached at its ends to the Windlass and the outermost section,and suitably connected to the intermediate section and the cross-head.

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upwardly and be guided by said dogs into the by-passes when the sectionsmove downwardly.

4. An extension ladder consisting of a plurality of sections slidablyarranged upon each other, the outermost and intermediate sections havinglongitudinal grooves, dogs which normally close the upper portions ofsaid grooves, said dogs having notches and extensions, by-passesextending around one side of the dogs and communicating with thegrooves, arms pivoted to the intermediateand innermost sections andhaving out-turned ends which traverse the grooves and the bypasses, saidends being arranged to successivel-y engage the dogs as they moveupwardly and be guided by said dogs into the by-passes when the sectionsmove downwardly, a cross-head for moving the innermost section upwardly,stops for limiting the upward movement of the cross-head, said stopsbeing located at a point slightly higher than the dogs, and means forinitially raising the intermediate section so that the crosshead willcontact with the stops while the lower arms on the innermost section arein engagement with the dogs on the intermediate section.

5. In an extension ladder, a section having longitudinal grooves andby-passes which latter communicate with the former, dogs pivoted to saidsection between the grooves and the by-passes and provided with notchesnear their upper terminals which latter are normally held in engagementwith one side of the grooves, a second section slidably mounted upon thefirst-mentioned one, and pivoted members carried by said second sectionarranged to traverse the grooves and the bypasses and successivelyengage the notches, substantially as described.

6. In an extension ladder, a section having longitudinal grooves andby-passes which latter communicate with the former, dogs pivoted to saidsection between the grooves and the by-passes and provided with notchesnear their upper terminals which latter are nor mally held in engagementwith one side of the grooves, a second section slidably mounted upon thefirst-mentioned one, pivoted members carried bysaid second sectionarranged to traverse the grooves and the bypasses and successivelyengagethe notches, and means forraising and lowering said sec ondsection.

7. An extension ladder consisting of a plurality of sections slidablyarranged upon each other, the outermost and intermediate sections havinglongitudinal grooves, dogs which normally close the upper portions ofsaid grooves, said dogs having notches and extensions, by-passesextending around one side of the dogs and communicating with thegrooves, pivoted members carried by the intermediate and innermostsections arranged to traverse the grooves and the by-passes and engagethe dogs as the sections move u wardly and be guided by said dogs into te by-passes when the sections move downwardly, a device for moving theinnermost section upwardly, stops for limiting the upward movement ofthe device, said stops being at a point slightly higher than the dogs,and a latch for holding the intermediate section while the innermost oneis being extended, said latch being provided with a member for initiallyraising the intermediate section so that the device will contact withthe stops while the lower pivoted members on the innermost section arein engagement with the dogs on the intermediate section.

In testimony whereof I affix my signature, in'the presence of twowitnesses.

FRANK A. BOBBITT.

Witnesses:

A. L. SHERMAN, F. G. FrsoHER.

